While Sceptile can do kinda well in OU, it's somewhat frail and it can easily be revenged by Scizor. Ferrothorn can pull off a similar job that Sceptile does, only that it's slower. If you want to keep Sceptile, that's fine:
-Stealth Rock/Spikes
-Leech Seed
-Power Whip/Protect
-Gyro Ball/Thunder Wave/Protect
Nature: Relaxed
EVs: 252 HP/88 Def/168 SDef
Item: Leftovers

Just to give Ferrothorn a bulky Water Pokemon to work with (since it works well with most Water Pokemon), you can go for Jellicent (for spinblocking) or Starmie (for fast sweeping):
Jellicent:
-Scald/Surf
-Toxic/Will-o-Wisp
-Recover
-Taunt
Nature: Bold
EVs: 248 HP/216 Def/44 Spe
Item: Leftovers